1. Field
Exemplary embodiments of the present invention relate to a semiconductor device and a semiconductor package.
2. Description of the Related Art
Consumer demand for mobile devices such as personal digital assistants (PDA), third-generation (3G) mobile phones, and digital sail cameras requires more capacity to run diverse applications and smaller size. Such need has been satisfied by employing fine processing semiconductor technology. However, as this technology has reached its limits due to increases in development periods and costs thereof a multi-chip package (MCP) technology is being adopted in mobile devices. A MCP refers to a complex chip product in which various semiconductor chips, such as, for example, NOR flash, NAND flash, SRAM, and UtRAM chips are mounted on a single package. In general, the MCP has a structure in which two, four or more of the same type semiconductor chips form a stack. Generally in an MCP the mounting area of the semiconductor chips forming the MCP may be reduced by 50% or more. The wiring of the semiconductor chips may also be simplified compared to using separate semiconductor chips. Accordingly, the cost of mobile devices may be reduced. Also, the productivity of the mobile devices may be improved.
In general, a semiconductor memory device, for example, a dynamic random access memory (DRAM), includes a data transmission circuit for outputting internal data to an external device. Furthermore, high-speed data transmission circuits for outputting data at the data rate of gigabits per second (Gbps) employ an emphasis method for reducing inter-symbol interference (ISI) jitter. A conventional emphasis method is described below.
FIG. 1 is a diagram showing gains in a data transmission circuit, a transmission line, and a data reception circuit without an emphasis operation (a) and with an emphasis operation (b).
Referring to FIG. 1, a data transmission line 120 has low pass filter characteristic due to parasitic resistance and capacitance. Accordingly, if an emphasis operation has not been applied (a), there may be a distortion in data transmitted by a data transmission circuit 110 through the data transmission line 120 so that a data reception circuit 130 receives data whose gain in a high frequency portion has been reduced.
An emphasis method may strengthen a high frequency component of a signal (or data) and send the strengthened signal by a data transmission circuit 110 by taking into consideration the aforementioned high frequency signal distortion. Hence, applying an emphasis method (b), the data transmission circuit 110 strengthens the high frequency component of a signal and outputs the strengthened signal. Accordingly, although the data transmission line 120 has a low pass filter characteristic, the data reception circuit 130 may receive a signal having the same gain for each frequency.
FIG. 2 is a diagram showing the waveform of data according to an emphasis operation in a conventional data transmission circuit.
Referring to FIG. 2, an emphasis operation may strengthen the level of data DATA when the data DATA shifts. For example, when the data DATA shifts from a low logic to a high logic, driving the data DATA to a “high” value is strengthened during a specific period. When the data DATA shifts from a high logic to a low logic, driving the data DATA to a “low” value is strengthened during a specific period. A high frequency component of the data DATA is generated at the moment when the data DATA shifts. Accordingly, an emphasis operation at the moment when the data DATA shifts may strengthen the high frequency component of the data DATA.
FIG. 3 shows the configuration of a data transmission circuit for performing an emphasis operation.
Referring to FIG. 3, the data transmission circuit may include an output driver 310, an emphasis driver 320, and an output pad 330.
The output driver 310 may be coupled to the output pad 330, and may drive the output pad 330 in response to output data OUT_DATA. The output driver 310 may pull-up drive the output pad 330 when the output data OUT_DATA is high data and may pull-down drive the output pad 330 when the output data OUT_DATA is low data.
The emphasis driver 320 may be coupled to the output pad 330, and may drive the output pad 330 in response to emphasis data EM_DATA. The emphasis driver 320 may pull-up drive the output pad 330 when the emphasis data EM_DATA is high data and may pull-down drive the output pad 330 when the emphasis data EM_DATA is low data. The emphasis data EM_DATA may be generated for driving the emphasis driver 320 so that the transition of the output data OUT_DATA is strengthened. The emphasis data EM_DATA may be generated by delaying and inverting the output data OUT_DATA. For reference, the driving force of the emphasis driver 320 may be set to have a specific ratio with respect to the driving force of the output driver 310.
A driver coupled to the output pad 330 functions as a load. Accordingly, if both the output driver 310 and the emphasis driver 320 are coupled to the output pad 330 as described above a load on the output pad 330 may be excessively increased.